Bacterial dysbiosis in newly diagnosed treatment naïve pediatric ulcerative colitis in Saudi Arabia.

BACKGROUND: The role of microbiota in the pathogenesis of ulcerative colitis (UC) has been increasingly recognized. However, most of the reports are from Western populations. In Middle Eastern countries, including Saudi Arabia, little is known about the role of microbiota. Therefore, our aim was to describe the bacterial microbiota profile and signature in pediatric UC in Saudi Arabia. METHODS: Twenty children with UC and 20 healthy controls enrolled in the study gave stool samples. Twenty rectal mucosal samples were taken from UC and 20 from non-UC controls. Inclusion criteria included newly diagnosed and untreated children and lack of antibiotic exposure for at least 6 months before stool collection was required for children with UC and controls. Bacterial deoxyribonucleic acid was extracted and sequenced using shotgun metagenomic analysis. Statistical analysis included Shannon alpha diversity metrics, Bray-Curtis dissimilarity, DESeq2, and biomarker discovery. RESULTS: The demographic characteristics were similar in children with UC and controls. There was a significant reduction in alpha diversity (P = 0.037) and beta diversity in samples from children with UC (P = 0.001). Many taxa were identified with log2 abundance analysis, revealing 110 and 102 species significantly depleted and enriched in UC, respectively. Eleven bacterial species' signatures were identified. CONCLUSIONS: In Saudi Arabian children with UC, we demonstrate a dysbiosis similar to reports from Western populations, possibly related to changes of lifestyle. Microbial signature discovery in this report is an important contribution to research, leading to the development of adjunctive non-invasive diagnostic options in unusual cases of UC.

KIF26A is mutated in the syndrome of congenital hydrocephalus with megacolon.

Human disorders of the enteric nervous system (ENS), e.g., Hirschsprung's disease, are rarely associated with major central nervous system involvement. We describe two families each segregating a different homozygous truncating variant in KIF26A with a unique constellation of severe megacolon that resembles Hirschsprung's disease but lacks aganglionosis as well as brain malformations that range from severe to mild. The intestinal phenotype bears a striking resemblance to that observed in Kif26a-/- mice where KIF26A deficiency was found to cause abnormal GDNF-Ret signaling resulting in failure to establish normal neuronal networks despite myenteric neuronal hyperplasia. Very recently, a range of brain developmental phenotypes were described in patients and mice with KIF26A deficiency and were found to result from abnormal radial migration and increased apoptosis. Our report, therefore, reveals a recognizable autosomal-recessive human KIF26A deficiency phenotype characterized by severe ENS dysfunction and a range of brain malformations.

Loss of FOCAD, operating via the SKI messenger RNA surveillance pathway, causes a pediatric syndrome with liver cirrhosis.

Cirrhosis is usually a late-onset and life-threatening disease characterized by fibrotic scarring and inflammation that disrupts liver architecture and function. While it is typically the result of alcoholism or hepatitis viral infection in adults, its etiology in infants is much less understood. In this study, we report 14 children from ten unrelated families presenting with a syndromic form of pediatric liver cirrhosis. By genome/exome sequencing, we found recessive variants in FOCAD segregating with the disease. Zebrafish lacking focad phenocopied the human disease, revealing a signature of altered messenger RNA (mRNA) degradation processes in the liver. Using patient's primary cells and CRISPR-Cas9-mediated inactivation in human hepatic cell lines, we found that FOCAD deficiency compromises the SKI mRNA surveillance pathway by reducing the levels of the RNA helicase SKIC2 and its cofactor SKIC3. FOCAD knockout hepatocytes exhibited lowered albumin expression and signs of persistent injury accompanied by CCL2 overproduction. Our results reveal the importance of FOCAD in maintaining liver homeostasis and disclose a possible therapeutic intervention point via inhibition of the CCL2/CCR2 signaling axis.

Viral dysbiosis in children with new-onset celiac disease.

Viruses are common components of the intestinal microbiome, modulating host bacterial metabolism and interacting with the immune system, with a possible role in the pathogenesis of immune-mediated diseases such as celiac disease (CeD). The objective of this study was to characterize the virome profile in children with new-onset CeD. We used metagenomic analysis of viral DNA in mucosal and fecal samples from children with CeD and controls and performed sequencing using the Nextera XT library preparation kit. Abundance log2 fold changes were calculated using differential expression and linear discriminant effect size. Shannon alpha and Bray-Curtis beta diversity were determined. A total of 40 children with CeD and 39 controls were included. We found viral dysbiosis in both fecal and mucosal samples. Examples of significantly more abundant species in fecal samples of children with CeD included Human polyomavirus 2, Enterobacteria phage mEpX1, and Enterobacteria phage mEpX2; whereas less abundant species included Lactococcus phages ul36 and Streptococcus phage Abc2. In mucosal samples however, no species were significantly associated with CeD. Shannon alpha diversity was not significantly different between CeD and non-CeD groups and Bray-Curtis beta diversity showed no significant separation between CeD and non-CeD samples in either mucosal or stool samples, whereas separation was clear in all samples. We identified significant viral dysbiosis in children with CeD, suggesting a potential role in the pathogenesis of CeD indicating the need for further studies.

Fungal Dysbiosis in Children with Celiac Disease.

BACKGROUND: Although intestinal fungi are known to interact with the immune system, the relationship between intestinal fungi and childhood celiac disease (CeD), an immune-mediated condition, has rarely been reported. AIMS: The aim of this study was to describe gut fungal profiles in a cohort of children with new-onset CeD. METHODS: Mucosal and fecal samples were collected from children with CeD and controls and subjected to metagenomics analysis of fungal microbiota communities. DNA libraries were sequenced using Illumina HiSeq platform 2 × 150 bp. Bioinformatic analysis was performed to quantify the relative abundance of fungi. Shannon alpha diversity metrics and beta diversity principal coordinate (PCo) analyses were calculated, and DESeq tests were performed between celiac and non-celiac groups. RESULTS: Overall more abundant taxa in samples of children with CeD included Tricholomataceae, Saccharomycetaceae, Saccharomycetes Saccharomyces cerevisiae, and Candida, whereas less abundant taxa included Pichiaceae, Pichia kudriavzevii, Pneumocystis, and Pneumocystis jirovecii. Alpha diversity between CeD and control individuals did not differ significantly, and beta diversity PCo analysis showed overlap of samples from CeD and controls for both fecal or mucosal samples; however, there was a clear separation between mucosal and fecal overall samples CONCLUSIONS: We report fungal dysbiosis in children with CeD, suggesting a possible role in the pathogenesis of CeD. Further larger, controlled, prospective and longitudinal studies are needed to verify the results of this study and clarify the functional role of fungi in CeD.

Tricho-hepato-enteric syndrome: Retrospective multicenter experience in Saudi Arabia.

Background: Trichohepatoenteric syndrome (THES) is a very rare disorder that is characterized by intractable congenital diarrhea, woolly hair, intrauterine growth restriction, facial dysmorphism, and short stature. Our knowledge of THES is limited due to the small number of reported cases. Methods: Thirty patients diagnosed with THES, all molecularly confirmed by whole exome sequencing (WES) to have biallelic variants in TTC37 or SKIV2L, were included in the study. Clinical, biochemical, and nutritional phenotypes and outcome data were collected from all participants. Results: The median age of THES patients was 3.7 years (0.9-23 years). Diarrhea and malnutrition were the most common clinical features (100%). Other common features included hair abnormalities (96%), skin hyperpigmentation (87%), facial dysmorphic abnormalities (73%), psychomotor retardation (57%), and hepatic abnormalities (30%). Twenty-five patients required parenteral nutrition (83%) with a mean duration of 13.34 months, and nearly half were eventually weaned off. Parenteral nutrition was associated with a poor prognosis. The vast majority of cases (89.6%) had biallelic variants in SKIV2L, with biallelic variants in TTC37 accounting for the remaining cases. A total of seven variants were identified in TTC37 (n = 3) and SKIV2L (n = 4). The underlying genotype influenced some phenotypic aspects, especially liver involvement, which was more common in TTC37-related THES. Conclusion: Our data helps define the natural history of THES and provide clinical management guidelines.

Clinical, Biochemical, and Molecular Characterization of Neonatal-Onset Dubin-Johnson Syndrome in a Large Case Series From the Arabs.

Background: There are only a few case reports and small case series on neonatal-onset Dubin-Johnson syndrome (DJS), particularly from Far-East Asia, Iranian and Moroccan Jews, and Europe. Objectives: In this first study from the Arabs and the largest series reported to date, we characterized the clinical, laboratory, and molecular features and outcome of gene-confirmed neonatal-onset DJS. Methods: We reviewed our database of 533 cases of neonatal cholestasis that presented to our center during the period from 2008 to 2019. We identified neonates with a disease-causing mutation in ABCC2 gene. Results: Twenty-eight neonates with DJS were diagnosed (5.3%). All of the 28 were full-term, well looking neonates without hepatosplenomegaly, with cholestasis, and normal liver synthetic function since the 1 week of life that resolved within 3-6 months of age, followed by a benign course punctuated by recurrent episodes of jaundice in 43% during a median follow up period of 9.25 (range 2.5-14 years). Alanine aminotransferase levels were within normal range in 26 patients (92%) and mildly elevated in two patients. ALT levels were significantly lower in neonates with DJS than in other cases with neonatal cholestasis from other causes (p < 0.001). The median urinary coproporphyrin I% was 88% (IQ1-IQ3 = 84.2-92.7%). We identified four homozygous variants in the ABCC2 gene (from 22 unrelated families), one splicing variant (c.3258+1G>A; p.?), and three were missense variants; two of which were novel missense variants [c.1594G>A (p.Glu532Lys) and c.2439G>C (p.Lys813Asn)]. The p.Gly758Val mutation has occurred in 23 patients (from 19 unrelated families). Conclusions: Our study suggests that normal ALT-cholestasis in a well-looking neonate should trigger evaluation for DJS. The p.Gly758Val variant in ABCC2 is the most predominant mutation among Arabs with "founder effects." Identification of the predominant ABCC2 variant in any population is likely to facilitate rapid molecular analysis by future targeting of that specific mutation.

Pathogenic STX3 variants affecting the retinal and intestinal transcripts cause an early-onset severe retinal dystrophy in microvillus inclusion disease subjects.

Biallelic STX3 variants were previously reported in five individuals with the severe congenital enteropathy, microvillus inclusion disease (MVID). Here, we provide a significant extension of the phenotypic spectrum caused by STX3 variants. We report ten individuals of diverse geographic origin with biallelic STX3 loss-of-function variants, identified through exome sequencing, single-nucleotide polymorphism array-based homozygosity mapping, and international collaboration. The evaluated individuals all presented with MVID. Eight individuals also displayed early-onset severe retinal dystrophy, i.e., syndromic-intestinal and retinal-disease. These individuals harbored STX3 variants that affected both the retinal and intestinal STX3 transcripts, whereas STX3 variants affected only the intestinal transcript in individuals with solitary MVID. That STX3 is essential for retinal photoreceptor survival was confirmed by the creation of a rod photoreceptor-specific STX3 knockout mouse model which revealed a time-dependent reduction in the number of rod photoreceptors, thinning of the outer nuclear layer, and the eventual loss of both rod and cone photoreceptors. Together, our results provide a link between STX3 loss-of-function variants and a human retinal dystrophy. Depending on the genomic site of a human loss-of-function STX3 variant, it can cause MVID, the novel intestinal-retinal syndrome reported here or, hypothetically, an isolated retinal dystrophy.

Enteroendocrine Dysfunction in Two Saudi Sisters.

Proprotein convertase (PC) deficiency is a rare autosomal recessive disorder caused by mutations in proprotein convertase subtilisin/kexin type 1 (PCSK1). It is characterized by severe malabsorptive early-onset diarrhea, obesity, and systemic endocrinopathies. Only few cases have been reported in the literature; we have add two female sisters with some difference in clinical progress. Herein, we describe two sisters with congenital osmotic diarrhea diagnosed with PC1/3 deficiency, causing malabsorptive diarrhea and enteroendocrine dysfunction, who presented with chronic enteropathy with hypernatremia but with different expressivity. PC1/3 deficiency presents with symptoms and signs that mimic glucose-galactose malabsorption. Because of the clinical paucity and heterogeneity of congenital enteropathies, whole-exome sequencing may be of great help towards early diagnosis and effective treatment.

What Do Saudi Children Ingest?: A 10-Year Retrospective Analysis of Ingested Foreign Bodies From a Tertiary Care Center.

OBJECTIVES: Few studies investigated the correlation between foreign body (FB) ingestion and occurrence of complications. The local literature is limited to case reports and small case series on esophageal FBs. We conducted this study to identify the high-risk factors predisposing to complications among Saudi children ingesting FBs. METHODS: The medical records of 436 children (boys, 59.6%; mean age, 4.4 ± 2.7 years) presenting to the emergency department (ED) between 2007 and 2016 were retrospectively reviewed. Relative risk analysis of clinical variables was performed between 2 groups: The first group constituted children without FB-related complications (n = 389), and the second group included those with major complications (n = 14). Major complication was defined as any event associated with significant morbidity such as esophageal stricture, esophageal perforation, esophageal fistula, and intestinal perforation or fistula formation. RESULTS: Most of the 436 cases presented between ages 2 and 4 years (35.1%). Coin was the most commonly ingested FB (22.9%) followed by button battery (19.5%). Most of the ingested FBs passed spontaneously without intervention (69%). Upper endoscopy was performed in 121 cases (27.7%). By multivariate analysis, the variables that were significantly associated with major complications included the following: very young age group (0-2 years; odds ratio [OR], 11.5), button battery (OR, 4), FB impacted at upper esophagus (OR, 8.7), and longer time duration to visit the ED (OR, 14.7). CONCLUSION: Button battery impaction at upper esophagus in very young children and delayed presentation to the ED were the most significant risk factors of FB-related complications.

Prevalence of nutritional disorders in Saudi children with inflammatory bowel disease based on the national growth reference.

BACKGROUND AND STUDY AIM: The prevalence of nutritional disorders in Saudi children with inflammatory bowel diseases (IBDs) has been reported using the World Health Organization (WHO) reference. Our aim was to provide more accurate definition of the prevalence of nutritional impairment in Saudi children with IBDs based on the national growth reference and to demonstrate the effect of using a reference from other populations on the prevalence rates. PATIENTS AND METHODS: Weight, height, and body mass index data, from the multicenter study of IBDs in Saudi children and adolescents, were plotted on the new Saudi national growth reference. Statistical analyses included frequency calculations and z-test for proportions to investigate the significance of the difference in prevalence. A p-value of < 0.05 was considered significant. RESULTS: Among a total of 374 patients, 119 (32%) had ulcerative colitis (UC) and 255 (68%) had Crohn's disease (CD). Compared with the WHO reference, the Saudi national reference produced a significantly lower prevalence of thinness in patients with UC (24% vs. 8%, p = 0.001), CD (35% vs. 20%, p = 0.002), and of short stature in patients with CD (28% vs. 11%, p < 0.001). The difference in the prevalence of overweight was not significant. CONCLUSIONS: We provide more accurate prevalence estimate of nutritional disorders in Saudi children with IBDs based on national reference. The use of the WHO reference overestimated the prevalence of thinness and short stature in Saudi children. Prevalence estimates based on references from other populations should be interpreted with caution.

Analysis of transcript-deleterious variants in Mendelian disorders: implications for RNA-based diagnostics.

BACKGROUND: At least 50% of patients with suspected Mendelian disorders remain undiagnosed after whole-exome sequencing (WES), and the extent to which non-coding variants that are not captured by WES contribute to this fraction is unclear. Whole transcriptome sequencing is a promising supplement to WES, although empirical data on the contribution of RNA analysis to the diagnosis of Mendelian diseases on a large scale are scarce. RESULTS: Here, we describe our experience with transcript-deleterious variants (TDVs) based on a cohort of 5647 families with suspected Mendelian diseases. We first interrogate all families for which the respective Mendelian phenotype could be mapped to a single locus to obtain an unbiased estimate of the contribution of TDVs at 18.9%. We examine the entire cohort and find that TDVs account for 15% of all "solved" cases. We compare the results of RT-PCR to in silico prediction. Definitive results from RT-PCR are obtained from blood-derived RNA for the overwhelming majority of variants (84.1%), and only a small minority (2.6%) fail analysis on all available RNA sources (blood-, skin fibroblast-, and urine renal epithelial cells-derived), which has important implications for the clinical application of RNA-seq. We also show that RNA analysis can establish the diagnosis in 13.5% of 155 patients who had received "negative" clinical WES reports. Finally, our data suggest a role for TDVs in modulating penetrance even in otherwise highly penetrant Mendelian disorders. CONCLUSIONS: Our results provide much needed empirical data for the impending implementation of diagnostic RNA-seq in conjunction with genome sequencing.

Liver Failure Among Young Saudi Infants: Etiology, Clinical Presentation, and Outcome.

OBJECTIVES: The published data on early infantile liver failure (EILF) are scarce and limited to Caucasians. We conducted this study to describe the etiology and outcome of EILF among Arabs and identify prognostic factors. METHODS: We retrospectively reviewed our database of 524 infants presenting with liver impairment from 2008 to 2018, and identified cases of EILF defined as presence of biochemical pattern of liver disease and INR ≥2 (unresponsive to vitamin K) with onset before 3 months of life. Primary outcomes included death or liver transplantation (LT) (poor outcome group) and survival with native liver (good outcome group). RESULTS: Forty-two cases of EILF (22 girls) were identified (8%). The etiology was indeterminate in 14 (33.3%) and established in 27 (64.3%): galactosemia (7 cases, 16.6%), tyrosinemia (5, 12%), neonatal hemochromatosis (NH), and hemophagocytic lymphohistiocytosis (HLH) (4 each, 9.5%]) mitochondrial hepatopathy (3, 7%), and miscellaneous (5, 12%). LF resolved in 15 cases (35.7%), either spontaneously or in response to specific therapy, 23 (54.7%) died, and 4 underwent LT (9.5%). ROC analysis for the best cut-off value of serum total bilirubin for prediction of study outcomes was 120 µmol/L (sensitivity 81.5%, specificity 80%). Among the diagnostic groups, galactosemia and tyrosinemia predicted good outcome, whereas the idiopathic diagnosis predicted poor outcome (OR = 13). CONCLUSIONS: Similar to Western countries, galactosemia, tyrosinemia, NH, HLH, and mitochondrial hepatopathy are the main players in EILF in Saudi Arabia. Galactosemia and tyrosinemia predict good prognosis and idiopathic diagnosis predicts poor prognosis.

Exome sequencing in routine diagnostics: a generic test for 254 patients with primary immunodeficiencies.

BACKGROUND: Diagnosis of primary immunodeficiencies (PIDs) is complex and cumbersome yet important for the clinical management of the disease. Exome sequencing may provide a genetic diagnosis in a significant number of patients in a single genetic test. METHODS: In May 2013, we implemented exome sequencing in routine diagnostics for patients suffering from PIDs. This study reports the clinical utility and diagnostic yield for a heterogeneous group of 254 consecutively referred PID patients from 249 families. For the majority of patients, the clinical diagnosis was based on clinical criteria including rare and/or unusual severe bacterial, viral, or fungal infections, sometimes accompanied by autoimmune manifestations. Functional immune defects were interpreted in the context of aberrant immune cell populations, aberrant antibody levels, or combinations of these factors. RESULTS: For 62 patients (24%), exome sequencing identified pathogenic variants in well-established PID genes. An exome-wide analysis diagnosed 10 additional patients (4%), providing diagnoses for 72 patients (28%) from 68 families altogether. The genetic diagnosis directly indicated novel treatment options for 25 patients that received a diagnosis (34%). CONCLUSION: Exome sequencing as a first-tier test for PIDs granted a diagnosis for 28% of patients. Importantly, molecularly defined diagnoses indicated altered therapeutic options in 34% of cases. In addition, exome sequencing harbors advantages over gene panels as a truly generic test for all genetic diseases, including in silico extension of existing gene lists and re-analysis of existing data.

Diagnostic delay of pediatric inflammatory bowel disease in Saudi Arabia.

BACKGROUND/AIM: Delay in the diagnosis of inflammatory bowel disease (IBD) is associated with complications. Our aim was to describe the pattern and risk factors associated with delay in the diagnosis of IBD in Saudi children. PATIENTS AND METHODS: This was a multicenter study with a retrospective/prospective design. Data on diagnostic delay in children with Crohn's disease (CD) and ulcerative colitis (UC) were retrieved from physician's notes. Multivariate regression analysis was used to assess the risk factors associated with long delay in diagnosis. RESULTS: There were 240 and 183 Saudi children with CD and UC, respectively. The median delays in diagnosis were 8 and 5 months in CD and UC, respectively, significantly longer in children with CD than UC (P < 0.001). Long diagnostic delays (>75th percentile) were 24 and 8.8 months for CD and UC, respectively. Ileal location was a significant risk factor in CD and the age of onset above 10 years was protective in UC. CONCLUSIONS: Long diagnostic delay in IBD was mainly due to the longer delay in gastroenterologist consultation. Review of the referral system is needed to focus on measures to reduce long delays in diagnosis. The ileal location as a risk factor in CD and age older than 10 years as protective in UC should help recognition and early referral.

Unusual Manifestation of Ulcerative Colitis.

The relationship of inflammatory bowel disease (IBD) and chronic recurrent multifocal osteomyelitis (CRMO) is understood as extraintestinal rheumatic manifestations. CRMO is a chronic, relapsing, inflammatory, noninfectious disorder of the skeletal system of unknown origin. The disease course is not always recurrent. The association of CRMO and ulcerative colitis (UC) is very rarely reported. We report a case of a 10-year-old Saudi female who was diagnosed with CRMO, when she developed fever in association with left foot pain, and ulcerative colitis was confirmed endoscopically and histologically based on a previous settled diarrheal illness and severe iron deficiency anemia which required blood. Both conditions responded well to IBD therapy. To the best of our knowledge, this is the first reported case of chronic, multifocal osteomyelitis associated with pediatric UC in Saudi Arabia. This report supports the use of IBD therapy in treating CRMO.

Outcome of biliary atresia among Saudi children: A tertiary care center experience.

BACKGROUND/AIMS: Data from Western countries indicate that biliary atresia (BA) is the leading cause of end-stage liver disease in children and the most common indication for liver transplantation (LT) in the pediatric population. There is no data on the epidemiology and outcome of BA in Saudi Arabia. The main objective of our study was to understand the clinical and epidemiological characteristics and outcome of BA in the Saudi population. PATIENTS AND METHODS: We retrospectively reviewed the database of infantile cholestasis cases that presented to our center from 2008 to 2015 and identified BA cases. Data on clinical, biochemical, imaging, and histopathological characteristics were collected by chart review. The two primary study outcomes were (1) successful Kasai portoenterostomy (KPE) defined as resolution of jaundice (total serum bilirubin <20 µmol/L) and (2) survival with native liver. RESULTS: Over the study period, we evaluated 450 cases of infantile cholestasis. In all, 21 cases (11 males) were diagnosed with BA (4.7%). BA cases were first seen by pediatric gastroenterologists at a median age of 65 days. KPE was performed in 12 cases at a median age of 73 days. Successful KPE was achieved in four cases (33%). Five of the remaining eight cases had LT and three died before LT. Nine of the 21 BA cases were denied KPE and had primary LT at median 8 months of age. The native liver 4-year survival rate was 14.3% and the overall survival rate was 81%. CONCLUSION: BA is an uncommon cause of infantile cholestasis in Saudi Arabia. Our study provides a snapshot of the epidemiology of BA in Saudi Arabia that is characterized by late referral to pediatric gastroenterologists and poor outcome without LT.

Biallelic RIPK1 mutations in humans cause severe immunodeficiency, arthritis, and intestinal inflammation.

RIPK1 (receptor-interacting serine/threonine kinase 1) is a master regulator of signaling pathways leading to inflammation and cell death and is of medical interest as a drug target. We report four patients from three unrelated families with complete RIPK1 deficiency caused by rare homozygous mutations. The patients suffered from recurrent infections, early-onset inflammatory bowel disease, and progressive polyarthritis. They had immunodeficiency with lymphopenia and altered production of various cytokines revealed by whole-blood assays. In vitro, RIPK1-deficient cells showed impaired mitogen-activated protein kinase activation and cytokine secretion and were prone to necroptosis. Hematopoietic stem cell transplantation reversed cytokine production defects and resolved clinical symptoms in one patient. Thus, RIPK1 plays a critical role in the human immune system.

Microvillus Inclusion Disease Variant in an Infant with Intractable Diarrhea.

Microvillus inclusion disease (MVID) is a rare autosomal recessive congenital enteropathy characterized by intractable secretory diarrhea. We report a case of MVID variant with a homozygous gene mutation in syntaxin 3 (STX3). The patient is a male Saudi infant who presented shortly after birth with severe vomiting, metabolic acidosis, and mild diarrhea. Electron microscopy study for small intestinal biopsy was consistent with MVID. MYO5B gene mutation was excluded; subsequently, whole exome sequencing (WES) was performed, which revealed homozygous gene mutation in STX3. Using WES in clinical environment can be a useful tool for diagnosing difficult and rare inherited congenital enteropathies.

Bile Acid Synthesis Disorders in Arabs: A 10-year Screening Study.

OBJECTIVES: Early diagnosis of bile acid synthesis disorders (BASDs) is important because, untreated, these conditions can be fatal. Our objectives were to screen children with cholestasis or unexplained liver disease for BASD and in those with confirmed BASD to evaluate the effectiveness of cholic acid therapy. METHODS: A routine serum total bile acid measurement was performed on children with cholestasis, liver cirrhosis, and liver failure. Patients were screened for BASD by fast atom bombardment ionization-mass spectrometry (FAB-MS) analysis of urine, and molecular analysis confirmed diagnosis. Treatment response to oral cholic acid (10-15 mg/kg bw/day) was assessed from liver function tests and fat-soluble vitamin levels. FAB-MS analysis of urine was used to monitor compliance and biochemical response. RESULTS: Between 2007 and 2016, 626 patients were evaluated; 450 with infantile cholestasis. Fifteen cases of BASD were diagnosed: 12 presented with infantile cholestasis (2.7%, 7 boys), an 8-year-old boy presented with cirrhosis, and two 18-month-old boys presented with hepatomegaly and rickets. Eleven were caused by 3ß-hydroxy-Δ-C27-steroid oxidoreductase dehydrogenase deficiency, 3 from Δ-3-oxosteroid 5ß-reductase deficiency, and 1 had Zellweger spectrum disorder. In all but 1, serum total bile acids were normal or low. With cholic acid therapy, 10 are alive and healthy with their native liver. Liver failure developed in 3 infants despite therapy; 2 died and 1 underwent liver transplantation. CONCLUSIONS: BASDs are rare but treatable causes of metabolic liver disease in Saudi Arabia. BASD should be considered in infants with cholestasis and low or normal serum total bile acid concentrations.